I first printed everything out of 3D Fuel PLa+ and when I assembled it and I inserted a 3D printed CMMG replica 22 mag, it snapped off the feed ramp at the base of the ramp. OK, so I’ll print the barrel adapter out of Fiberon PA612CF, anneal it for 12 hours, and let it sit out for moisture. Assembled everything today and the bolt wouldn’t fully close at first until I forced it closed. And…the feed ramp split at the base of the ramp again. It looks like the bottom of the metal reinforcement plate is striking the top of the feed ramp, as the Fiberon version now has a dent.
Another odd thing with both, the adapter pin holes for the handguard don’t anlign evenly with the cuts in the RS22 barrel. There is maybe an 1/16” (or less) of the barrel that shows on the feed ramp side of the pin holes. It takes a hammer to get one of the pins through both holes and the barrel cutouts. Additionally, dummy rounds would eject with the PLA+ barrel adapter but not the Fiberon one.
Anyone else experiencing this issue with the Wisp and an RS22 barrel?
Before I even read the whole post, I was going to say, your bolt is hitting it and causing it to break. But then you confirmed it. Guide says to file an angle on the bottom of the reinforcement plate or it will hit the feed ramp. It’s also why you had to force the bolt closed. Nothing should be forced.
The other issue might be from not being calibrated. Every filament shrinks/expands differently. Nylons can shrink after annealing but expand after moisture conditioning so can be more tricky. CF/GF tend to be tighter inside and out because of the fibrous surface. Rossi also isn’t known for their precision manufacturing so it may not fit perfectly. Holes are always made smaller to be drilled out since a loose hole is a lot more of an issue. They also never print nicely round. I’m sure every guy agrees tight holes are better than loose holes.
I always like to mention the wisp is considered an advanced build and requires advanced 3d printing skills and gunsmithing knowledge. Bolt actions are more difficult to build correctly than a blowback semi auto.
I’m not new to building guns from parts or from P80 kits, just 3D printed ones. I wasn’t sure how much to file the bottom of the reinforcement plate. I took the edge off, but now I understand the need to file it some, test fit, and file again if still too tight. I was worried about filing too much and it not stripping the next round…but this makes sense. I miss Reddit, but I do appreciate this site and I greatly appreciate your feedback! If nothing else, this gets more discussion going regarding the Wisp…as there isn’t too much about it online and it seems like a really neat project. I’ve had fun so far, but should’ve stuck with Polymaker. I’m not as much a fan of the 3D Fuel filament.
As for the Rossi barrel, it was hard to pass up a threaded RS22 barrel for $37 shipped as part of their BF discounts.
Different issue, as I resolved the headspace issue by further filing the reinforcement plate…thanks for the clarifying feedback! I also removed the extraction issue after discovering a small burr on the underside of the extractor that needed to be filed down. My current concern deals with the amount of horizontal barrel sway with the RS22 barrel within the barrel adapter. I’ve printed in both PLA+ and PA612-CF, and both result in the barrel moving up to a half inch (or less) to the right and left. I discovered I needed to increase the supports angle to 31 to get the supports to properly print the reduction area within the adapter. The barrel naturally rests off center to the left…or the handguard and upper incorrectly sit off to the right. It’s like a brace is needed toward the end of the handguard to keep the barrel centered and free of sway. Or does the guide comment to JB Weld the adapter to the barrel also apply to OEM barrels and not just DIY barrels?
This has been quite an educational build and makes me want to join a beta so I can learn even more from the development process.
Rs22 barrel should be the most stable attachment with the pins going all the way through the receiver. So is the play in the adapter to barrel or adapter to receiver? If there is any need for a brace than something isn’t fitting correctly.
It seems to be a bit of play in both the barrel to the adapter and the adapter to the receiver. PLA+ adapter is providing the tighter fit with the PLA+ upper. I decided to wrap a couple layers of teflon tape around the barrel, but fewer layers around the pin holes in the barrel. It Is now a much tighter fit in the adapter. I actually added additional layers another two or three times after test fitting each attempt.
I then wrapped the barrel adapter with a couple layers of teflon tape as well and it is much better than before. Instead of just under 1/2” horizontal sway of the barrel, it is now down to probably 1/8” or even less. It seems to be a tolerance issue…and that may be a result of the RS22 barrel itself since it was a $35 barrel shipped from Rossi. I further bubba’d it with a black ziptie around the barrel from each side of the end of the handguard and now it is really rocksteady. The two zip ties are pulling equally from both the right and left sides of the handguard. I know my experience is not what is intended, but it seems cable ties and pipe/duct clamps are a natural fit for 3D2A anyway.
As for settings, I printed all the Polymaker PLA+ with 300BLK’ settings. Now I just need to get to a range to finally test it with live ammo, as dummy rounds are functioning quite well. Again, this has been an educational and fun project that reminds me of working out the kinks in the first P80 I built.
I’ll need to tighten the adapter tolerances then.
How can I join the discord? Although it manually cycles fine with metal dummy rounds, the headspace must be too large for actual rounds. After detonation, the rear 1mm or so of the casing is bulging and preventing extraction. I’d like to see how the beta resolved the headspace issues.
Likely an issue with tolerance stacking. With rs22 it’s a bit harder to adjust since the barrel can’t be moved in easily. It would be best if I release bolts with different length options so people can choose the right one that fits.
Eventually I’m going to do a different design (replica this time) with a receiver in a chassis bolt action with a multi piece receiver so headspace can be adjusted easier.
Here are photos of one of the casings that got stuck, though I didn’t think they looked too bad. But there is a little bulge in front of the rim.
I’ve updated the files with alternate length bolts. The guide now also explains one way of measuring headspace since I got asked that a lot.